**Core Concept**
Tuberculin testing, also known as the Mantoux test, is a diagnostic tool used to assess the presence of latent or active tuberculosis (TB) infection. The test involves injecting a small amount of tuberculin into the skin, and the resulting skin reaction is measured after 48-72 hours.

**Why the Correct Answer is Right**
The optimal time for reading the tuberculin test is between 48-72 hours after injection, as this allows for the accurate assessment of the skin reaction. A delayed hypersensitivity reaction occurs in individuals with a previous exposure to TB, causing the skin to become inflamed and form a raised reaction. The reaction is typically measured in millimeters, with a larger reaction indicating a stronger immune response.

**Why Each Wrong Option is Incorrect**
**Option A:** Immediate reading after injection (less than 24 hours) may not accurately reflect the immune response, as the skin reaction may not have fully developed.
**Option B:** Reading the test after 7-10 days may result in false-negative reactions, as the immune response may have waned over time.
**Option C:** Reading the test at any time before 48 hours may not provide a reliable assessment of the immune response, as the skin reaction may not have reached its peak.

**Clinical Pearl / High-Yield Fact**
It is essential to note that a negative tuberculin test result does not rule out active TB infection, and a positive result may be seen in individuals with a previous BCG vaccination or other non-TB infections.

**Correct Answer: C. 48-72 hours.**